Square Kilometer Array Design (SKADS)

“平方公里阵列”(SKA)将是一个国际射电望远镜，收集面积为100万平方米-相当于大约200个足球场/使SKA比位于约德雷尔银行的曼彻斯特大学的洛维尔望远镜大200倍。这项为期四年的平方公里阵列设计研究(SKADS)汇集了欧洲和国际天文学家，以制定和商定最有效的设计。最终的设计将使SKA能够以前所未有的详细程度探测宇宙，回答关于宇宙的基本问题，例如“什么是暗能量？”以及“我们今天在星系中看到的这种结构实际上是如何形成的？”SKA的概念首先被用来观测氢气的特征射电发射。对氢信号的测量将使天文学家能够定位和称量10亿个星系，这也将极大地检验爱因斯坦的广义相对论，也许还会证明它是错误的。这将是射电天文学家发现的一长串基本发现中的一部分，包括类星体、脉冲星和大爆炸辐射。设计将于2010年完成，并于2020年建成全面运营的SKA。SKA的另一个目标是脉冲星；它是恒星爆炸的旋转残留物，是宇宙中最精确的时钟。脉冲星的质量是地球的一百万倍，但只有大城市的大小，它每秒可以自转数百次。有了SKA，我们将发现一颗脉冲星绕着黑洞运行，通过观察时钟频率的变化，我们可以判断爱因斯坦是否对引力有最后的定论。实现这些科学目标所需的仪器的规模是巨大的，整个大陆总共有100万平方米的收集面积，但实现仪器潜力所需的技术在许多方面更令人望而生畏。SKADS的工作是基于相控阵接收器。当放置在传统的大规模生产的无线电“碟子”的焦点时，这些阵列就像广角无线电摄像机一样观察大片天空。位于SKA中心的一个单独的、大得多的相控阵不断地扫描天空。在未来四年3800万美元的资金总额中，欧盟委员会提供了催化剂资金的27%。英国已经投资了由PPARC提供的560万英镑(约合830万英镑)的资金。英国贡献了SKADS项目的30%。英国正专注于复杂的数字相控阵以及SKA将产生的海量数据的分发和分析。英国SKADS的主要技术设计目标是生产一种双极化全数字相控阵‘瓦片’，大约1米乘以1米，因此称为‘2-PAD’。这将是阵列天线单元设计的一系列基本系统设计研究的高潮；用于天线关键低噪声放大器(LNA)的极低成本半导体以及将接收信号放入数字域的极高速模数转换器(ADC)；大量研究在成本和功率方面负担得起的超高速数字处理技术，以及减少设备外部和自身感应的干扰。这一开发预计将成为项目结束时可用于天文目的的性能最高的相控阵瓷砖。当用于选定的天文观测时，将调查模拟SKA的要求和性能。结果将是得出SKA目标规格的关键，并将被工程小组广泛使用。为了找到最优配置，将对完成的SKA的通信和计算资源进行模拟。将研究和演示分发非常准确的时间信号的技术。这对于使用有时相隔数千公里的许多接收系统的射电望远镜来说是至关重要的。

The 'Square Kilometre Array' (SKA) will be an international radio telescope with a collecting area of one million square metres - equivalent to about 200 football pitches / making SKA 200 times bigger than the University of Manchester's Lovell Telescope at Jodrell Bank. The four-year Square Kilometre Array Design Study, SKADS, brings together European and international astronomers to formulate and agree the most effective design. The final design will enable the SKA to probe the cosmos in unprecedented detail, answering fundamental questions about the Universe, such as 'what is dark energy?' and 'how did the structure we see in galaxies today actually form?' The SKA concept was first proposed to observe the characteristic radio emission from hydrogen gas. Measurements of the hydrogen signature will enable astronomers to locate and weigh a billion galaxies It will also test Einstein's General Theory of Relativity to the limit / and perhaps prove it wrong. It will add to the long list of fundamental discoveries made by radio astronomers including quasars, pulsars and the radiation from the Big Bang. The design will be complete by 2010 and building SKA with full operation in 2020. Another target for the SKA is pulsars; spinning remnants of stellar explosions which are the most accurate clocks in the universe. A million times the mass of the Earth but only the size of a large city, pulsars can spin around hundreds of times per second. With the SKA we will find a pulsar orbiting a black hole and, by watching how the clock rate varies, we can tell if Einstein had the last word on gravity or not. The scale of the instrument needed to fulfil these science goals is huge, a total of 1,000,000 square metres of collecting area spread across a continent, but the technology required to fulfil the potential of the instrument is in many ways more daunting. The SKADS effort is based on phased array receivers. When placed at the focus of conventional mass-produced radio 'dishes', these arrays operate like wide-angle radio cameras observing huge areas of sky. A separate, much larger, phased array at the centre of the SKA constantly scans the sky. Catalyst funding has been provided by the European Commission of 27% of the total of ¤38M funding over the next four years. The UK has invested £5.6M (¤8.3M) funding provided by PPARC. The UK's is contributing 30% of the SKADS programme. The UK is concentrating on sophisticated digital phased arrays and the distribution and analysis of the enormous volumes of data which the SKA will produce. The main technological design aim of UK SKADS is to produce a dual polarisation all-digital phased array 'tile' approximately 1m by 1m, so call '2-PAD'. This will represent the culmination of a number of fundamental system design studies into array antenna element design; very low cost semiconductors for the critical low noise amplifiers (LNAs) at the antenna and the very high speed analogue to digital converters (ADCs) which put the received signal into the digital domain; considerable research into very high speed digital processing techniques which are affordable in terms of cost and power and the reduction of interference both external and self-induced by the equipment. This development is expected to be the highest performance phased array tile for astronomical purposes available at the end of the project. The requirements and performance of a simulated SKA will be investigated when used for selected astronomical observations. The results will be key to deriving the target specification for the SKA and will be used extensively by the engineering groups. The communication and computing resources of a completed SKA will be simulated in order to find the optimal configurations. Techniques for distributing very accurate time signals will be worked upon and demonstrated. This is vital to a radio telescope using many receiving systems sometimes separated by thousands of kilometres.